The present invention relates generally to an apparatus and method for removing undesired granular particles that may remain on surfaces of an article surrounding a cavity that has been filled with the granular particles. More particularly, the invention provides an apparatus and method for removing scattered granular particles from surfaces of a combined filter rod made up of filter components and particle filled cavities.
Certain articles of manufacture such as charcoal cigarette filters, individual-sized packets of granular food products or condiments, capsuled pharmaceuticals, ammunition and the like require repetitive placement of precisely metered charges of particulate matter at some location along the production-line of the articles.
The high speed production of a quality product requires that accurate amounts of the granular particles be inserted only into desired cavities, with excess particles being removed from the surrounding surfaces of the article while the article continues to be processed at high speeds. While it has been known to apply vacuum to remove scattered material from sites intended to be free of material so as to enhance cleanliness of the operation, existing means for removing scattered particles from the undesired areas have suffered from the problem of also removing particles from the desired locations such as particle filled cavities. This problem has been compounded during high speed manufacture of articles such as cigarette filter rods since no means has been provided to prevent the application of vacuum over areas of the article where granular particles should not be disturbed, while at the same time ensuring that undesired particles that have been vacuumed are removed completely.
In view of the above problems of prior art systems for cleaning articles during manufacture, the present invention is embodied in a system that includes a ported wheel rotating around a stationary vacuum chamber, and a stationary shoe or vacuum applicator that is positioned between the ported wheel and an article or articles having cavities to be filled with particles. The article or articles can be moved along a vacuum rail underneath the ported wheel so that the cavities travel in synchronization with the ports in the ported wheel. The placement of ports in the ported wheel and the design of the stationary shoe allow the system to clean particles from different length surfaces of the article interspersed between the cavities where it is desired to leave the particles undisturbed.
The ports through the ported wheel allow vacuum to be communicated from a stationary vacuum chamber within the wheel to the stationary shoe or vacuum applicator. The stationary shoe is provided with at least one concave upper surface segment that conforms closely to the outer circumferential surface of the ported wheel. The concave top surface of the stationary shoe can be divided into segments having different lengths in the direction of rotation of the ported wheel, with the different length segments being spaced in a direction parallel to the axis of rotation of the ported wheel and aligned with axially spaced ports of different lengths in the ported wheel.
A radial hole or slot is provided through the stationary shoe from the concave upper surface to a lateral groove or slot across the bottom surface of the stationary shoe. The lateral groove or slot across the bottom surface of the stationary shoe is positioned in close proximity to the top surface of an article, such as a cigarette filter rod, that is passing underneath the stationary shoe. In an embodiment of the invention, the article passing underneath the stationary shoe and rotating ported wheel can be a combined cigarette filter rod having alternating filter components and particle filled cavities. The particle filled cavities can be spaced along the filter rod at different distances from each other, separated by longer and shorter filter components.
As the filter rod travels underneath the stationary shoe and the ported wheel, the ported wheel is rotated in synchronization with the travel of the filter rod. As the filter rod travels under the stationary shoe, a tapered leading edge of the shoe scrapes loose particles from the surface of the filter rod. As a port in the ported wheel reaches the radial passageway through the stationary shoe, vacuum from the stationary vacuum chamber within the ported wheel is communicated through the radial passageway and through the cross groove on the lower surface of the shoe. This results in an air flow across the portions of the filter rod passing directly underneath the cross groove, which pulls away scattered particles that may lie on the filter components in between the particle-filled cavities. The timing of the ported wheel and the length of the port that is passing over the radial passageway through the shoe are predetermined such that air is only drawn across the filter component sections of the combined filter rod and, as a result, does not remove particles from the particle-filled cavities.
As the ported wheel continues to rotate past the point where vacuum is communicated through the port to the radial passageway through the stationary shoe, the port then begins to pass beyond the end of the concave segment it is aligned with on the upper surface of the stationary shoe such that ambient air is pulled through the port into the stationary vacuum chamber to completely remove any loose particles that have been removed from the surface of the article.